This invention relates to a radio communication apparatus for carrying out communication by the use of a radio signal. The radio communication apparatus may be a radio paging receiver, a transceiver, or the like although description will be mainly directed to the radio paging receiver.
Various conventional signals can be used as the radio signal in the radio paging receiver. One of the conventional signals includes a POCSAG (Post Office Code Standardisation Advisory Group) code as proposed by the British Post Office. The POCSAG code consists of a preamble signal and a plurality of batches which follow the preamble signal.
A conventional radio paging receiver includes a memory, a receiving unit, an announcing unit, and a control unit. The memory unit in for memorizing an identification number specific to the radio paging receiver. The receiving unit is for receiving the radio signal to produce a received signal which will be described in the following. The announcing unit is for announcing an announce to inform a user of the paging receiver of reception of the radio signal. The control unit is for controlling the announcing unit in accordance with the received signal with reference made to the identification number.
The received signal carries an intermittent succession of frames each of which comprises a first and a second codeword. Each of the first and the second codewords includes a call number and is supplied with a signal condition.
It will be assumed that the signal condition becomes worst when one of the codewords is influenced by noise and others. In this case, the announce may be an erroneous one. This is because the control unit carries out comparison between the identification number and the call number received within a predetermined error range and controls the announcing unit in accordance with a result of the comparison. Each codeword may be received within the predetermined error range even when the signal condition is appreciably unfavorable.